So, I purchased a Sabertooth Z77 a few days ago and started setting it up today. I tried a test boot and I get a cpu fan error (I'm using a Cooler Master Hyper 212 Evo heatsink). I tried connecting the fan to different headers and still get the same message. The fan starts up fine, then I hear the post beep, then it slows down to about 600rpms (it does the same thing with the chassis fans). I tried connecting it to my old mobo (also an asus board), and it runs at full speed. I tried connecting the fan directly to the psu, and it also runs at full speed. I'd prefer not to contact Asus unless absolutely necessary so any help would be appreciated.
I figured it out. I didn't realize that Asus' Q-fan controller was controlling the speed of the fans connected to the motherboard. I just went into the bios and disabled it and the cpu fan is going full speed now. Thanks for the reply jaquith.